1. Field of the Invention
The present invention relates to an electrical connector device for use in a vehicular steering system, and more particularly to an electrical connector device for electrically connecting an actuator for an air bag system to a collision sensor between relatively rotatable members of a steering system.
2. Description of the Prior Art
There have been known air bag systems which include an air bag normally collapsed to be housed in a steering wheel or another vehicular member and inflatable to provide cushioning against damaging impacts which passengers would otherwise be subjected to in an automobile accident. Such air bag systems also include a collision sensor which is attached to a vehicle frame and, upon detection of a vehicle collision requiring air bag inflation, delivers a signal to an actuator for detonating an explosive in order to release or produce a pressurized gas which, together with air, is introduced into the air bag to inflate the latter.
The air bag is normally housed centrally in the steering wheel with the actuator and gas generator disposed adjacent to the air bag. Because the steering wheel and steering shaft are rotatable with respect to the vehicle frame, the collision sensor and the actuator are required to be electrically connected to each other by a suitable electrical connector means which provides electrical connection between mutually rotatable members.
One known such connector means comprises a slip ring mechanism including a slip ring and a brush which are movable relative to each other and held in frictional contact with each other. The slip ring and brush assembly, however, tends to wear through repeated use, tends to fail to provide good electrical contact, and hence is unable to operate stably for a long period of time. The known mechanism is also disadvantageous in that abrasive contact between the brush and the slip ring causes wearing thereof into metal powder which is liable to cause short-circuiting, the brush and slip ring assembly generates noise signals which adversely affect a supplied pulse signal and hence invite malfunctioning of the air bag system, and there is a tendency to produce sparks between the brush and the slip ring. The connector device suffering from these difficulties is not considered optimum for use with the air bag system which is a most important safety device that is required to be absolutely reliable and stable in operation.
On the steering wheel there are also mounted actuator switches for actuating horns or alarming devices. An electrical connector for such actuator switches, when disposed separately from the connector device for the air bag system, would require additional parts for attachment, would be complicated in structure, and could not be assembled with ease.
The connector device disposed between the relatively rotatable members is necessarily constructed of a rotatable component supported on the rotatable member including a steering wheel and a steering shaft and a stationary component supported on the fixed member such as a steering column. Where the steering assembly is equipped with a power steering mechanism of the rack-and-pinion type rotational power of the steering wheel produces an axial thrusting force acting on the steering shaft by a helical angle between a pinion on a lower end of the steering shaft and a rack held in mesh with the pinion, whereupon the rotatable member is caused to move slightly upwardly with respect to the fixed member. Therefore, the connector device should allow relative axial movement of the mutually rotatable members between which the connector device is disposed.